Trans-1-chloro-3,3,3-trifluoropropene (hereinafter, 1-chloro-3,3,3-trifluoropropene may be referred to as “1233zd” or merely as “1233”) is useful as a raw material for a foaming agent for a hard polyurethane foam, a solvent, a cleaning agent, a cooling medium, a working fluid, a propellant, a fluorinated resin, etc. As an example of conventional techniques relating to the present invention, Patent Document 1 discloses a method for obtaining 1-chloro-3,3,3-trifluoropropene by reacting 1,1,1,3,3-pentachloropropane with hydrogen fluoride in the gas phase. Additionally, Patent Document 2 discloses a method of reacting 1,1,1,3,3-pentachloropropane with hydrogen fluoride in the absence of a catalyst thereby obtaining 1,1,1-trifluoro-3-chloro-2-propene (1-chloro-3,3,3-trifluoropropene). Furthermore, Patent Document 3 describes, as a method for producing 1-chloro-3,3,3-trifluoropropene, a process involving the step of causing a reaction of 1,1,1,3,3-pentachloropropane in a reactor vessel in the presence of a Lewis acid catalyst or a mixture containing a Lewis acid catalyst at a temperature of lower than 150° C. in the liquid phase, the step of continuously retrieving products in the reactor vessel (hydrogen chloride and 1-chloro-3,3,3-trifluoropropene) and the step of isolating 1-chloro-3,3,3-trifluoropropene obtained by the preceding step.
In the above-mentioned methods, however, 1-chloro-3,3,3-trifluoropropene is usually obtained in the form of a mixture of cis and trans isomers, which is disadvantageous when either one is put to use.
In view of the above, attempts had been made to interconvert them by isomerization; Patent Document 4 discloses a process of taking advantage of chemical equilibrium to transform trans-1-chloro-3,3,3-trifluoropropene into cis-1-chloro-3,3,3-trifluoropropene.
Additionally, Patent Document 5 mentions in Examples about isomerization of 1-chloro-3,3,3-trifluoropropene, in which when fluorinating trans-1-chloro-3,3,3-trifluoropropene to provide 1,1,1,3,3-pentafluoropropane there occurs isomerization reaction as a side reaction thereby producing cis-1-chloro-3,3,3-trifluoropropene.
Though isomerization reaction of Patent Document 4 was studied in the use of a fluorinated chromia oxide catalyst as a fluorinated catalyst, the yield of trans-1-chloro-3,3,3-trifluoropropene at reaction temperatures of 103-199° C. is low (58.9-70.2%). The product of Patent Document 5 is just a by-product. Accordingly, these methods are not always suitable for the industrially actual use.